Most Inter-city trains arrive at Termini Station.
A few trains, particularly those arriving at night, arrive at Tiburtina
or Ostiense stations.

Termini Station

The hub of Rome's transport system can be confusing when you first arrive
, but the following explanations of its layout should help you get oriented.
Once you have gotten off the train and have walked down the platform,
you will reach the main gallery. The exit by platform 1 will take you
to the north side of Termini; the exit by platform 22 will take you to
the south side of Termini. Continuing away from the platforms past the
main gallery, you will reach the main hall. Exiting from the main hall
you will find Piazza dei Cinquecento, the largest bus terminal in Rome,
where the access to the city's two metro (subway) lines, A and B is also
located. The night bus to Fiumicino airport stops here as well, although
you'll have to look very hard for the sign.

Tiburtina Station

The second biggest train station in Rome, easily accessible by bus and
metro (Line B) from the center. The slower (and cheaper) train and night
bus to Fiumicino airport leave from here. Facilities at the station include
a 24 hour supermarket and exchange office. Across the piazza in front
of the station you will find the buses that depart for destinations all
over Italy and abroad. The ticket offices are located in the piazza and
around the corner on Circonvallazione Nomentana. From Termini: Line
B stop Tiburtina or Bus 492.